In the conventional video compression technology, a bit stream is encapsulated in a network abstraction layer (NAL) unit. The NAL unit provides a self-contained packet and gives a video layer identity in different network environments. A header of the NAL unit contains information used in a system layer. The header of the NAL unit becomes a part of the packet header used in a packet network, and is designed to operate by media aware network elements (MANEs).
The NAL unit header in the conventional technology includes the following syntax elements: nal_ref_flag which indicates whether the NAL unit is used for reference in a decoding process of another NAL unit; nal_unit_type which indicates a type of a content transmitted by the NAL unit, where the NAL unit contains information such as a parameter set, a coded slice, or a supplemental enhancement information (SEI) message; and temporal_id which indicates a temporal identifier of the NAL unit.